The hsqldb used by OOo Base supports links to csv text files.
See http://www.hsqldb.org/web/hsqlDocsFrame.html.
This can be done in Base as follows:

1 - Open a new Base DB.

2 - Create text file "letter_code.csv" with contents below.
Put this file in the same directory as the new Base DB.
(See docs for how to link to files elsewhere.)

3 - Select Tools > SQL and enter the following commands
CREATE TEXT TABLE "letter_code" (F1 INTEGER, F2 VARCHAR(10))
SET TABLE "letter_code" SOURCE "letter_code.csv"

4 - Tables created from Tools>SQL do not appear in the Table
Container area until Base is closed and re-opened so close
and re-open base. (Maybe there is a better way to refresh
the contents of the Table Container area.)

5 - Now open the table to verify the result.
See the docs for more information.


contents of "letter_code.csv"
1,"a"
2,"b"
3,"c"
4,"d"
5,"e"
6,"f"
7,"g"
8,"h"
9,"i"
10,"j"
11,"k"
12,"l"
13,"m"
14,"n"
15,"o"
16,"p"
17,"q"
18,"r"
19,"s"
20,"t"
21,"u"
22,"v"
23,"w"
24,"x"
25,"y"
26,"z"